In a Phase change Random Access Memory (PRAM) device, a state of a phase change material may be used to store information thereby providing non-volatile memory. Phase change materials may exhibit at least two different states, referred to as the amorphous and crystalline states. Transitions between the amorphous and crystalline states may be selectively initiated, for example, using current induced temperature cycles. The states may be distinguished because the amorphous state generally exhibits a higher resistivity than the crystalline state. The amorphous state may have a more disordered atomic structure, and the crystalline state may have a more ordered atomic structure. Generally, any phase-change material may be used in a phase change memory device, but thin-film chalcogenide alloy materials have been found to be particularly suitable.
In a phase change memory device, the phase of a phase change material in a memory cell may be reversibly changed back and forth between the amorphous and crystalline states. In effect, each phase change memory cell may be a programmable resistor that reversibly changes between higher and lower resistance states in response to temperature cycles induced by resistive heating. Phase change memory devices are discussed, for example, in U.S. Pat. No. 6,507,061.